Photodegradation of piroctone olamine in aqueous

0 downloads 0 Views 377KB Size Report
ï □%. 1. The ç ç% B+G,v. Iï ؛ھ}ç n). ¡ GB}
p;7;· ; · 6 H• - H pR(C8 RCp _ d_~ myy]myo r ww_

si/aries ,. studiesJ 'h am ed.¡

sented '.~ 11 th~ ~ crvcd, of the >F ­F W ï >G■WG ■ ï ■% 1. The ç ç% B+G,v Iï ºª}ç ¡ GB }G " º -----r ww' ; · ¡n ---·----- - ; ] ] · ] ] ] ] · · ]· · - -------; ï ■% · n 1

vitro HWBï

ç

r

­ï BF" ■ n · ■B; J.

,KER " YF%G r ' J,

l. MATERIALS AND METHODS

(■ B+G ó}G>G■B %ï ?o;r • fQ• ï ■% y;u • fQ• º"} B+G ¡ " ª >G~, Gí G■ (" } B+G +ª ¡ ï ■ rw, · n rur ; It F> ï ­>" >BïO­G F■ >ª }ºï WBï ■B>" ­ª B F" ■>, ï ■ F■%F >óG■>ï O­G ó}G}GLª F >FBG (" } B+G º"}¡ ª ­ï BF" ■ " } ï >+ï ¡ ó" " /(, Jv;

1. Chemicals · F}" WF " ■W" ­ï ¡ F ■Wd9 W B" óF}" Y, 6 " GW+>BHN~" } (]++ ó" U%G}; lt F> " %" ª }­G>> ï ■%Wï óï O­G " } %GW" ¡ ó" >F ■• ª ■%G} B+G ï WBF" ■ " } +Gï B d ( Ju B" ( Jyº R~, >" ­ª O­G F■ Uï ­G} ï Bu;' a dUfU~ ï ■% F■ ï Lª G" ª > >" ­ª BF" ■> " } >ª }ºª W B■■B> ï B ( B" rua dUfU~;

­■ B+F> >Bª %BG% B+G GººG WBFí G■G>> " } óF }" WF " ■W " ­ï ¡ F ■Wï • ï F ■>BPityrospannn ovale, ï ■% FB> >ï ºGB< º"} ª >G " ■ +ª rrr ï rr +ï F} UF B+ ï ó}" ­ï ­" ¡ GB}FW¡ GB+" % ( (9 (; x G ï ­>" >Bª %FG% B+GW+ï ■• G> ï >+ï ¡ ó" " (" ■■ª ­ª BW%UF B+ u;ya óF}" WB" ■W" ­ª ¡ F■W ª ■%G}UG■BUFB+ BF ¡ G r r r r ï ■%B+G QF ■GBFW > " } ó+" B" %W• }ï %ï BF "■ B+F> ¡ " ­GW ª ­G ï Bï W" ■WG ■B}ï B F" ■ ■Gï } { .O. ( O·' - F■ ï Lª G" ª > >" ­ª BF" ■ UF B+ " } UF B+" ª Bï ■F" ■FW>ª} ºï WBï■B>; 7+G >+ï ¡ ó" " Uï > ó­ï WG % F■ ï ó}" ¡ F■G■Bó" >FB F" ■ F■ " }%G} B" BG>Bó+" B" >Bï OF ­F B< B" G>Bï O­F >+ B+G >Bï OF ­F B< " } >ª O>Bï■WG> ï ■%W" >¡ GBFWó}" %ª WB> UF B+ }G>óGWBB" ­F• +BGYó" >ª }G, ï ■%B" %G¡ " ■>B}ï BGB+ï BB+G óï WQï • F■• ó}" í F%G> >ª F Bï O­G ó}" BGWBF" ■ ­}" ¡ ■" }¡ ï ­ GYó" >ª }G ( ( ' r ;

2. Photodegradation of solutions of piroctone olamine

or

p" ­ª B F " ■> " } óF }" W B" ■G " ­ï ¡ F ■G ï B ï W" ■WG■B }ï B F" ■ " º { ;um; ( o-) - F■ Uï BG} ï ■% ï Bï W" ■WG■B}ï BF" ■ " } { ;' m; (u· 5 - F■ Uï BG} UF B + J;ya >" %F ª ¡ ï ­Qª ­­ï BG d7WYï ó" ■ 8 ' y ï ■% 7GYï ó" ■ 8 muyufyu; 6 G■QG­~F■ ó" ­B UG}GGYó" >G% myy

Photodegradation of piroctone o/amine in aqueous dilute-çi--solutio Effect of the presence o_f anionic-§urfacla, M. T. Le, L.J.M. Coiffard, F. Peigné and ·y_ de Roeck-HoltzhaL

S.T.P. PHARMA SCIENCES 6 (6) 455-458 1996

cH3

-!"

3

CH{

f:

~HJ _,,...CH,

...._

CH2

Table I - Photodegradation of aqueous solution of piroctone olamin ·---· Absorbency· C (mol/I).1 o·• Time (min) C/Co

)I_ __ ~ CH2

~

o 20 40 60 80 100 120 140 ·160

O

O-

+ H3 N-CH2 -CH2-0H

~-----------------

Figure 1 - Chemical structure of piroctone olamine. lis molecular weight is 298.4.

to the light source in the light stability cabinet (Original Hanau, No.7011, Original Hanau Quarzlampen GmbH). The intensity of UV A and UVB was mesured with an Osram apparatus (Centra-UV-Meßgerät). This intensity was maintained at 6.45 and 1.47 rnw.cm? for UVA and UVB, respectively. The analysis was carried out on duplicate samples and the difference between the duplicates was less than I%.

0.500 0.423 0.372 0.332 0.306 0.274 0.255 0.243 0.224

7.04 6.09 5.36 4.78 4.41 3.95 3.67 3.50 3.22

1.000 0.865 0.761 0.679 0.626 0.561 0.521 0.497 0.457

where C and Co are the concentrations ol'piroctone olarnine timet and initially and k" is the apparent first order degradath rate constant. In the absence of surfactant, the rate constant is 4.80.10·-1 rnin'. In addition, we observe a decrease in the r­ of 0.30 unit during the manipulation.

3. Assay 2. Effect of anionic surfactants Piroctone olamine was determined by a spectrophotometric method (Hitachi UV-visible double beam spectrophotometer, model U-2000). Oprunum scnsitiviry ofpiroctone olamine was obtained at 298 nm. Under the experimental conditions, a linear response (correlation coefficient, r = 0.99997) was obtained over piroctone olnmine concentrations ranging lrorn 10 to 50 µg/ml.

However, we estimated the influence of the presence anionic surfactant on the photodegradation of piroctoneolami in aqueous solution with 3.5% of Texapon N25 and Texap N40 (50/50) added. The concentration of this solution piroctonc olarnine was 7.24.10-5 Mand the pl-I 7.20.

li. RESULTS AND DISCUSSION

[igure 4. This figure demonstrates the gradual decrease

A set or UY spectra obtained during photolysis is shown absorbency at 298 nm during photolysis and a slight deviatj or the maximum or absorbency towards 287 nm. The degradar¡ rate constant was calculated from the slope of the line absorbency versus time. The percentage of substance rcmainu

1. Kinetics of piroctone olamine degradation The photodegradation of piroctone olaminc was expressed as the rate of change of absorbency at 298 nm. A set of UV spectra obtained during photolysis is shown in [igure 2. This figure demonstrates the gradual decrease in absorbency at 298 nm during photolysis. The degradation rate constant was calculated from the slope of the line of absorbency versus time. The percentage of substance remaining was calculated from Beer's plot or concentration versus absorbency (table/). The photodegradation of piroctone olamine in diluted aqueous solution (figure 3) followed apparent first order kinetics and is described by the following equation :

■ -



■ o

o

ù

0.1 .__ _ _,_ ·••--+------+---··i---+---+-----lf------i 100 120 140 16' o 20 60 30

"'º

Timó tnun)

C!Co = e•k' "

L--------··---------·- ------

Eq. I

Figure 3 - Photodegradation of piroctone olarnine in aqueous dilut solution at pH 7.00.

1.0 1.0

>u e

Q)

>o

a

.o

ö

e QJ

£J

o

C/)

.o

U)